The present invention provides a method, a device and a system for processing data during idle listening. The method includes: sampling, in an idle listening mode, a first analog signal by using an N-bit ADC, and sampling, in a transceiving mode, a second analog signal by using an M-bit ADC, where N and M are both integers, and N is less than M. Embodiments of the present invention can reduce power consumption of an ADC during idle listening.